A smart city can achieve comprehensive perception, interconnection, and convergence of information, thereby greatly enriching people's life and communication. Building a smart city is inseparable from an information detection and transmission system that is based on, for example, the Internet of Things (MTC, machine type communication). The Internet of Things detects and collects information about a surrounding environment system by using widely distributed sensors, and transmits the information to a cloud computing-oriented information processing center by using a wireless transmission system.
Currently, a technology is known, in which, for example, user equipment (UE) in a Long Term Evolution (LTE) system is properly simplified, for example, only a single mode, a single band, a single RF chain, or a single antenna mode is performed, and the simplified user equipment is used as MTC user equipment, so that the MTC user equipment (hereinafter MTC UE for short) can access LTE. Because the MTC UE uses a simplification technology, an access range of an LTE network that the MTC UE can access is 5-9 dB or even more less than an access range of the user equipment in LTE (hereinafter LTE UE for short).
On the other hand, for example, a smart metering (such as a water meter and an electricity meter) system in the MTC UE is generally deployed in a basement, which leads to an increase of a transmission path loss (about 20 dB); therefore, in comparison with the LTE UE, a 20 dB additional loss is introduced (or rather, the access range decreases by 20 dB).
That is, in general, in comparison with the LTE UE, the access range of the MTC UE decreases by about 30 dB; as a result, the MTC UE cannot access a base station, which seriously affects a communication effect, a use effect, and user experience of the MTC UE.
To compensate for this part of loss, it is proposed that a multiple-retransmission technology be used in MTC, so as to enhance communication performance. However, by means of performance emulation, it is found that hundreds of retransmissions need to be performed in order to compensate for the 30 dB loss. On one hand, use efficiency of a radio spectrum is greatly reduced; on the other hand, a corresponding design modification to a base station is required by a retransmission mechanism, which causes incompatibility between a base station supporting MTC and a base station not supporting MTC, and further affects normal communication of the LTE UE.
Therefore, a technology is in need that can improve a communication effect and user experience of a low capability terminal device incapable of directly accessing an access network device.